Above figure from Kim et. al, "Is It Feasible to Build New Land in the Mississippi River Delta?," Eos Trans. AGU, 90(42), 373, 2009. Copyright 2009 American Geophysical Union. Reproduced/modified by permission of American Geophysical Union.
Answering 10 Fundamental Questions About the Mississippi River Delta
With growing recognition of the need to restore the Mississippi River Delta, the questions turn to practical matters such as the feasibility of restoration, its effects on industry and the long-term needs of a changing coast.
As part of our ongoing effort to document the best possible science in the field of deltaic restoration, our Science and Engineering Special Team published a summary report, "Answering 10 Fundamental Questions About the Mississippi River Delta," in April 2012. This research tackles the primary questions surrounding restoration in the region.
Answer summaries are below, and the full report is linked here.
Question 1: Is there enough sediment to restore the delta?
The Mississippi River Delta is a dynamic place, where water and wetlands are constantly shifting with natural patterns of erosion and growth. Because of this, there has never been enough sediment to sustain the entire delta at one time. There have always been areas that are actively growing while other areas disappear. Recent decades have also seen the sediment supply of the Mississippi River cut in half by dams upriver. Still, the amount of available sediment is large enough to build and sustain wetlands in targeted areas of the coast. (Read more)
Question 2: Are diversions useful tools for building land?
Large-scale problems require large-scale solutions. By using the river's sediment to mimic natural deltaic patterns, properly designed diversions have the potential to build and sustain substantial amounts of land. (Read more)
Question 3: Will diversions introduce nutrients that harm wetland vegetation?
Although nutrients introduced by diversions will have some impacts on vegetation, particularly on the distribution of certain plant species, the cost of inaction is higher. Without large-scale restoration that provides a source of sediment and fresh water, the delta's wetlands will continue to degrade into open water. Thus, any negative effects of higher nutrient input are outweighed by the larger benefits for the entire coast. (Read more)
Question 4: Will diversions harm fisheries?
Species will react in different ways to changes in the coastal landscape, but research indicates that large-scale sediment diversions can support the overall health of fisheries by returning the system to a more sustainable baseline. Without action, the status quo will prove ruinous for fisheries and the communities dependent on them. (Read more)
Question 5: How will restoration affect navigation?
Ongoing land loss in the Mississippi River Delta threatens the long-term viability of Louisiana's navigation system. Since the 1920s, the river has been straitjacketed by a levee system known as the Mississippi River and Tributaries Project, which is responsible for a large amount of land loss in the region. Revising the current management scheme and conducting large-scale restoration is the best way to protect this vital navigation system over the long term. (Read more)
Question 6: Can levees alone provide enough flood protection?
As recent disasters have shown, levees alone cannot be relied on to provide all the protection needed for coastal communities and infrastructure. In some cases, by damaging wetlands and encouraging unwise development, levees actually increase exposure to flood and storm risks. Though a valuable asset in some places, levees should be only one of multiple lines of defense. (Read more)
Question 7: Will restoration measures displace communities?
Some communities will be affected by salinity changes and a shift in coastal resources, but the larger threat lies in continued land loss. Without restoration, delta residents will grow increasingly vulnerable to flooding and other disasters. Ultimately, the lack of restoration will force people from their homes. However, by coordinating restoration and mitigation projects, we can provide positive outcomes for communities. (Read more)
Question 8: What does the economy stand to lose if we do not restore the delta?
The economy of coastal Louisiana is worth hundreds of billions of dollars. Without restoration, the region's economic health is at serious risk. (Read more)
Question 9: Why should restoring the delta be a national priority?
The Mississippi River Delta is one of America's greatest landscapes. But just as it supports a dizzying array of biodiversity, so it also supports the economy of much of the United States. A lot depends on sustaining the region's navigation, flood control, energy production and commercial fishing. Each of these functions is currently at severe risk from the degradation of the region's coastal wetlands. The delta's problems are national in scope and deserve a national response. (Read more)
Question 10: Is restoration feasible given climate change and rising energy costs?
Climate change and rising energy costs pose significant threats to the delta's current management system. Maintaining the status quo will be disastrous for navigation, flood protection and restoration efforts. However, by addressing land loss, the delta can be put on a sustainable path, even with sea level rise. By rebuilding wetlands, we can improve the long-term viability of the region's deep draft navigation, storm protection and economy. (Read more)